Thunderbolt Bridge Speeds

[MagnumOP]

I’m connecting a Mac Pro (7,1) to an M2 Pro Mac Mini using a Thunderbolt cable with the hope to use the Thunderbolt Bridge feature to get a high performance network connection between the two machines.

The connection seems to be limited to 10 gigabits/s despite Thunderbolt 3’s limit of 40 gigabits/s.

Has anyone been able to achieve speeds faster than 10 gigabits/s?


Note: the cable I am using is not the bottleneck. It is a Thunderbolt 3 cable that is only 0.7 meters long.

 

[startergo]

Both TBT3 And 4 use USB3 for a host-to-host network connection. PCIe is NOT used for inter-domain network connection.

Therefore, TBT network speeds are capped at “10gbps” (or more like 9Gbps after protocol overhead). TBT is simply attaching a network driver to a 10Gbps USB3 connection to achieve host-to-host networking.

 

[joevt]

I don't think it's USB. If it was USB then you would see it as a USB device somewhere.

The Thunderbolt NHI devices of each Mac are communicating with each other using something other than USB or PCIe. Thunderbolt networking works in macOS, Linux, and Windows. I suppose you might be able to see how it works by looking at the Linux Thunderbolt drivers.

 

[startergo]

There is some experimental data:

Chris Bergeron Tech Blog

In this post I discuss how you can upgrade a NAS Server by adding Thunderbolt 3 for lightning fast connectivity at 20 or 40Gbps. This particular implementation is specific to an Apple Mac Mini M1 and

chrisbergeron.com

 

[joevt]

There is some experimental data:

He was getting near 20 Gbps between a Mac and Linux but the connection was not correctly setup as 40 Gbps x1. Instead, it was doing 20 Gbps x2.

He got slightly greater than 20 Gbps when using two Macs (40 Gbps x1 link).

That's definitely more than USB 10 Gbps and even USB 20 Gbps.

I wonder what two Linux machines would give (if they can connect at 40 Gbps x1).

 

[MagnumOP]

Thanks for all the help everyone!

 

[TzunamiOSX]

Both TBT3 And 4 use USB3 for a host-to-host network connection. PCIe is NOT used for inter-domain network connection.

Therefore, TBT network speeds are capped at “10gbps” (or more like 9Gbps after protocol overhead). TBT is simply attaching a network driver to a 10Gbps USB3 connection to achieve host-to-host networking.

Ähhhh, and why does a TB2 to TB3 network work? TB2 does not have USB3 integrated.